Method of combating weeds using nu-substituted carbamates of 2, 4, 5-trichloro, 6-nitro phenol



United States Patent O METHOD OF COMBATING WEEDS USING N-SUB- STITUTED CARBAMATES F 2,4,5-TRICHLOR0, 6-NITRO PHENOL Joseph A. Lambrech, Charleston, W. Va., assignor to Union Carbide Corporation, a corporation of New York No Drawing. Application November 23, 1956 Serial No. 623,825

7 Claims. (Cl. 712.6)

This invention relates to new compositions of matter, a method for their preparation and to herbicidal com positions containing them. More particularly, the present invention relates to aryl N-alkylcarbamates, as new compositions of matter, to a method for preparing them and to herbicidal compositions containing them.

The compounds of the present invention may be represented by the general formula:

wherein A is a member selected from the group consisting of hydrogen, nitro, halogen, and alkyl containing from 1 to 4 carbon atoms, inclusive; B is a member selected from the groupconsisting of hydrogen, halogen 2,933,383 Patented Apr. 19, 1960 wherein R is a member selected from the group consist: ing of hydrogen, alkyl containing from i to 8 carbon atoms, inclusive, and alicyclic radicals containing from 5 to 6 carbon atoms, inclusive; R is a member selected from the group consisting of hydrogen, hydroxyl and alkyl containing from 1 to 8 carbon atoms, inclusive; and R is a member selected from the group consisting of CH -0-CH -C H -CH -CH and Hz-N 2 Illustrative examples of said compounds are:

Compound No. Formula Name 0 GON(CH2)1 00 ON(CH:):

O CON(CH:)1

4-Ch1orophenyl N,N-dlmethylcarbamate; B. Pt.

108-ll0l2 mm. Hg; Sp. G. 1.234 20 C./20 O.

2,4-Dich1oropheny1 N,N-dimethy1carbamate; B. Pt.

120l23/3 mm. Hg.

S-Ohlorophenyl N,N-dimethylcarbamate; B. Pt.

-107/2 mm. Hg; Sp. G. 1.226 20l20 O.

2-Nitropl1enyl N,N-dimethylcarbamate; B. Pt. 142l3 mm. Hg; Sp. G. 1.245 20l20 G.

Z-ChlorophenYl N,N-dimethylcarbamate; B. Pt.

112l2 mm. Hg.

2,4igg3ntrophenyl N,N-dimethylcarbamate; M.P.==

The present compounds may be prepared by reacting phosgene with a substituted sodium phenolate to form a phenoxy, carbonyl chloride. This acid chloride is then reacted with an amine to form the carbarnate. The following equations graphically illustrate these reactions:

wherein A, B, F, D, E and Y have the same meanings as given in columns 1 and 2, lines 27-80 and 1-29 of this specification.

Compound No. Formula i CHZOHI 0 OCON OH=GH CaHn I 20..." 0m 01 2,4,5-Trlchloro-6-nitrophenyl N-(MyclopentenyDN-(Z- V ethylhexyUcarbamate; Residue.

C1 v. v

CHzCH: 3K OCON OH=GH 0H: t 27...... ON 01 2,-4,5Trichloro-6-nltro henyl N-(z-eyclo nteny1)-N-; methyl carbamate: asldue. I 5

I p 01 I OCONHOH omc1 2,4.5griehlorsfi-nltrophenyl N-hydroxyc'arbamsts;

OOONHCH: i

o1 2,4,5-Trichlorophenyl N-metn lcarbamateiar. l2.5 mm.; Sp. G. 1.392 20l20 C.

OCONHOH 30..-... Cl 2,4 b5 -zlgchlorophenyl N-hydroxycarbamste M.P.=

OCONHI a m 0,: or 2,4,5-Trlchloro-6-nitrophenylcarbnmate;1Vl P.=196 c. 5

product, without further purification, but can be isolated I:

by distillation, if desired.

The reaction of the chloroformate with ammonia or an amine can be carried out in presence of solvents, such as water and dioxane. The reaction should be conducted at a temperature in therange of15 C. to 50 C. Below 15 C. the reaction rate is too slow and above 50 C.

the reaction rate is so rapid that loss-of the low boiljng amines occur and some decomposition takes place.

For the most part, the compounds of this invention are crystalline solids which can be isolated by filtration or centrifugation and dried. They are insoluble or only 9 EXAMPLE 1 2,4,5-trichloro-6-nitrophenyl chloroformate was prepared by slowly adding 60 parts of phosgene to 500 parts oftoluene at -10 C. The phosgene, toluene mixture was allowed towarm up to C. and then 132 parts of sodium 2,4,5 -trichloro-6-nitrophenolate was added through a powder funnel. The reaction is exothermic so that it is necessary to apply external cooling to maintain the: reaction temperature at 0 C. An additional amount of phosgene, about 20 grams was added to the reaction mixture to complete the reaction. Thesodium chloride-that was formed was removed by filtration, the toluene was removed; by distillation. and. the residuewas heated to 90 C. at 2 mm. Hg to remove any low boiling material. The 2,4,5-trichloro-6-nitrophenyl chloroformateis i used in the synthesis of'th'e carbamates without further purification and is taken as the residue from the above de-, scribed distillation.

2,4,5 -trichloro-6-nitrophenyl N,N dimethylcarbamate was prepared by adding dropwise 0.46, gramtmolestof 2,4,5-trichloro-6-nitrophenyl chloroformate to a mixture of 1 gram mole of dimethylamine and 300 cc. of dioxane at 25 C. After the addition of thechloroformate, the reaction mixture was heated at 55 C. for one hour. The mixture was cooled to 20 C. and the dimethylamine hydrochloride was removed by filtration. The dioxane was then removed by distillation. The product crystallized on cooling. It was washed with about 150 cc. of water and dried. It is a yellow crystalline solid which meltsat170," C.

EXAMPLE 2 2,4 5-trichloro-6-nitrophenyl N-methylcarbamate was prepared by slowlyadding 152 grams of 2,4,5-trichloro- 6-nitrophenyl chloroformate to a mixture of 100,. grams.

of a 39 percent water solution of 'methylamine and 100 grams of water at 25 C. After the addition of the chloroformate, the mixture was heated at 50 C. for one hour. Upon cooling a solid precipitated. It was filtered from the mother liquor washed with several 200 cc. portions of water and air dried. This solid is a product which melts at. 155 C. with decomposition. Nitrogen analysis, found 9.4 percent; theory 9.8 percent.

EXAMPLE 3 2,4,5-trich1oro-6-nitrophenyl carbamate was prepared by slowly adding 151 grams. of' 2.4,5-trichloro-6-nitrophenyl chloroformate to a mixture of 150 grams of a 28 percent water solution of ammonia and 100 grams of water at 20-25 C. After the addition of the chloroformate, the mixturewas gradually heated to 40 C. and held at that temperature for 30 minutes. The reaction mixture was then cooled to C. and the solid-which separated was filtered from the mother liquor, washed with water and air dried. The recovered product is a crystalline solid which melts at 196C.

EXAMPLE 4 2-nitrophenyl chloroformate was prepared by heating 42 parts of sodium hydroxide, 139 parts of 2'-nitrophenol, and 800 parts of water at 80C. for one hour. The sodium Z-nitrophenolate solution was cooled to 25 C. and then 100 parts of phosgene in 300 parts of toluene was added dropwise through a dropping funnel. The reaction is exothermic so that it is necessary to apply external cooling to maintain the reaction temperature at 25 C; The toluene layer was separated from the water layer and the toluene layer was distilled. The 2-nitrophenyl chloroformate is a light yellow liquid which boils at 105 C. at 2 mm. Hg.

10 EXAMPLES 2-nitrophenyl N,N-dimethylcarbamate was prepared by.

adding dropwise 86 partsof 2-nitrophenyl chloroformate to amixturepf. 42 parts of dimethylamine and 300 parts of dioxane at 25 C. After the addition of the chloroformate, the reaction mixture was heated at 50 C. for- The mixture was cooled to 20 C. andthe one hour. dimethylamine hydrochloride was removed by filtration. The reaction mixture was then distilled in a one foot unpacked column. The 2-nitrophenyl N-dimethylcafi bamate is a light yellow liquidywhich boils at 143 C. at 3 mm. Hg and has a specific gravity of 1.245 at 20 C.

EXAMPLE 6 2-nitrophenyl-morpholinyl N car'ooxylate was prepared by slowly adding 101 parts of Z-nitrophenyl chloroformate to a mixture of 87 parts morpholine and 400i parts-of dioxane at 30 C. After the addition of the chloroformate, the reaction mixture was'heated at 50.- C. for one hour. The mixture: 'was cooled to 20 C. and

the morpholine hydrochloride was removed by filtration. The dioxane was removed by distillation and the product distilled in a one foot unpacked column. The Z-nitrophenyl morpholinyl-N-carboxylate is a light yellow solid which boils at 192 C. at 2.5mm. Hg and melts at 81C.

EXAMPLE 7 2,4-dinitrophenyl chloroformate was prepared by slowly adding 220 parts of phosgene to 2000 parts of toluene at.

-10 C. The phosgene, toluene mixture was allowed to warm up to 0 C: and then 492 parts of sodium 2,4-dinitrophenolate was added through a powder funnel. The reaction is exothermic so thatit is necessary to apply external cooling to maintain the reaction temperature at 0 C. Thesodium chloride that .was formed was removed" by filtration, the toluene, was removed by distillation and the residue was heated to 80 C. at 2 mm.,Hg to remove any low boiling material. The,2,4-dinitrophenyl chloroformate is used 'in the synthesis of the carbamates without further purification and is taken ,as the residue from the;

above described distillation.

2,4-dinitrophenyl N-N-dimethylcarbamate.was prepared by adding dropwise l23tparts of 2,4-dinitrophenyl chloroformate to a mixture of 50 parts dimethylamine and 500 parts dioxane at 25 C. After the addition of the chloroformate, the reaction mixture-was heated at 50 C. for

one hour. Theprodllct' crystallized on cooling. It was washed thoroughly with water to-rern'ove the dimethylamine hydrochloride; The 2,4-dinitrophenyl N-dimethylcarbamate wasthen dried. It is a yellow crystalline solid which melts at 192 C.

EXAMPLES 2,4-dinitrophenyl diisopropylcarbamate was prepared.

EXAMPLE" 9 2,4,5-trichloro-6-nitrophenyl N-cyclopentenyl N-2- ethylhexylcarbamate-wasprepared by adding dropwise parts 2,4,5-trichloro-6rnitrophenyl chloroformate to a mixture of 98 partsrcyclopentenyl, Z-ethylhexylamine and If 300 parts of dioxane at 25 C. After the addition of the chloroformate, the reaction mixture was heated at 45 C. for one hour. The dioxane was then removed by distillation. .Product dissolved in ethyl ether and washed thoroughly with water to remove the cyclopentenyl 2-ethylhexylamine hydrochloride. Ethyl ether then removed by distillation and the residue was heated to 90 C. at mm. Hg to remove any low boiling material. The 2,4,5-trichloro-fi-nitrophenyl N-cyclopentenyl N-Z-ethylhexylcarbamate is a dark viscous liquid and is a residue product. 4 r

EXAMPLE 2,4,5-trichloro-6-nitrophenyl N-hydroxycarbamate was prepared by adding dropwise .152 parts of 2,4,5-trichloro- 6-nitrophenyl chloroformate to a mixture of 69 parts of hydroxylaminehydrochloride; 40 parts sodium hydroxide, and 400 partswater at 2 5 C. After the addition of the chloroformate, the reaction mixture was heated at 60 C.

for one hour. The mixture was cooled to C. and the product crystallized. It was washed with about 1000 parts of water to removethe hydroxylamine hydrochloride and product dried. It is alight red crystalline solid which melts at 142 C. a

p The compounds of the present invention can be incorporated with various materials to prepare new herbicidal compositions, either in liquid or solid form. These herbi cidal compositions are applied either as sprays or dusts to the area to be protected from undesirable plant growth. They are effective for the pre-emergence suppression of weeds and can also be applied as aqueous foliage sprays to control established weeds selectively, that is without injury to the crop plant. These compositions are particularly effective for the control-of weeds in planting such as corn, snapbeans and soybeans. T

The herbicidal dust compositions are compounded to give homogeneous, free flowingdusts by mixingthe carbamates with finely divided inert solids or extenders such as talcs, natural clays, diatomaceous earth, pyrophyllite and flours such as cottonseed and walnut shell flours.

Concentrated water dispersible liquid compositions can be prepared by incorporating with the carbamates variousorganic liquid diluents such asacetone, methyl ethyl liquid formulations of the herbicidal compositions, a surface active agent should preferably beused. These agents cause the compositions to be easily dispersed in water to give aqueous sprays which constitute va desirable method of application. The surface active'agents employed can be of the anionic, cationic or nonionic type and include, for example, sulfonated animal and vegetable oils, sulfonated petroleum oils, sodium lauryl sulfate, glycerol monostearate ethylene oxide condensation products with octylphenol, lauryl pyridinium bromide and cetyldimethylbenzyl ammonium chloride. The surface active agent, when used, should comprise from 1 percent to 15 percent by weight of the composition.

The percentage by weight of the essential active ingredients may vary according to the manner in which the composition is to be applied but, in general should'comprise 0.5 to 95 percent by weight of the herbicidal composition. 6

The relative activity of the various carbamate derivatives is shown by the following experimental evidence:

Test as Germinative Seed Toxic-ants;

' TABLE I PercentGermination Number Radish Rye Grass Check; no treatment 84 1 72 40 2 72 48 3 48 12 4 44 152 5 64 i 68 a o 4 7- s4 0 5: 88 .0' 9 2 64 10 96 o: 12 Y 64 1 as 1% 36 24:- 14-- 4 '0- 15 72 '40- 1a 60 so. 17 so 44 1s 16 19 0 .0, 2o 3s 40 21 4 0., 22 O :0 as I o 0' 24 v 0 v 8: 25 o p 0 9s v as as 27 68 7s 2s 0 o 29 84 24- so so a a1 0 as A series of tests were conducted in the field in plots, of 16 square feet, for preand postemergence selective" seeding of corn, snapbeans and soybeans. The compounds tested were applied to the fields in aqueous media at the indicated dosages. The weed ratings and crop response values were determined by comparison with control plots. The results are given in Table II. The abbreviations used in Table II are as follows:

Weed Rating Crop Response 1-G0od Control. A-No injury. 2-Fair Control. B-Slight injury. 3-None. G-Moderate injury. D-Severe injury.

. E-Plant dead.

TABLE II Pro-Emergence Dosage,

, Ompd. No. lbs. per. Crop Response acre Weed Rating Corn Soy Snap Bean Bean 10 1 A A 10 1 A A A 5 1 A A A 10 1 A B A 10 1 A 0 0 wherein R is selected from the group consisting of hy: drogen, lower alkyl and hydroxyl substituted lower alkyland R is a, member selected from the group consisting of hydrogen, hydroxyl, lower alkyl and hydroxyl sub;

stituted lower alkyl.

13 2. An aryl N-alkyl carbamate having the general formula:

wherein R is selected from the group consisting of hydrogen, lower alkyl and hydroxyl substituted lower alkyl and R is a member selected from the group consisting of hydrogen, hydroxyl, lower alkyl and hydroxyl substituted lower alkyl.

3. 2,4,5-trichloro 6 nitrophenyl N,N dimethylcarbamate.

4. 2,4,S-trichlormG-nitrophenyl N-methylearbarnate.

5. 2,4,5-trichloro 6 nitrophenyl N,N-di-(Z-hydroxyethyl) carb amate.

6. 2,4,5-trichloro-6-nitrophenyl carbamate.

7. 2,4,5-trichloro-6-nitrophenyl N,N-dibutylcarbamate.

References Cited in the file of this patent UNITED STATES PATENTS 1,252,451 Kropp Ian. 8, 1918 2,209,245 Bartholomaus July 23, 1940 2,776,197 Gysin et a1. Jan. 1, 1957 2,791,603 Bavley et a1. May 7, 1957 FOREIGN PATENTS 450,184 Germany Oct. 1, 1937 128,292 Sweden May 30, 1950 1,031,976 France Dec. 24, 1954 1,101,980 France Oct. 12, 1955 OTHER REFERENCES Beilstein, vol. 6 (2nd ed.), pp. 172 and 224.

Beilstein, vol. 6 (4th ed.), p. 233.

Kolbezen: I. Agr. Food Chem., vol. 2, pp. 864-70 (1954). 

1. THE METHOD OF COMBATTING WEEDS WHICH COMPRISES APPLYING TO A LOCUS TO BE PROTECTED A HERBICIDAL AMOUNT OF A COMPOUND HAVING THE GENERAL FORMULA: 